Geology Exam 1 Study Guide Notes

Scientific Method

• Steps of the Scientific Method include:

  • Observation

  • Hypothesis formulation

  • Experimentation

  • Data collection

  • Analysis

  • Conclusion

  • Communication

Earth Systems: Spheres of the Earth

Atmosphere

• Layers of the Atmosphere include:

  • Troposphere: Closest to Earth's surface, weather occurs here.

  • Stratosphere: Contains the ozone layer; protects Earth from UV radiation.

  • Mesosphere: Meteors burn up, very cold temperatures.

  • Thermosphere: High temperatures, contains the ionosphere.

  • Exosphere: Outermost layer, where atmospheric particles are so sparse they can travel hundreds of kilometers without colliding.

Geosphere

• Layers of the Geosphere include:

  • Inner Core: Solid, composed mainly of iron and nickel.

  • Outer Core: Liquid, generates Earth's magnetic field.

  • Mesosphere: Rigid and solid layer beneath the asthenosphere.

  • Asthenosphere: Semi-plastic, allows tectonic plates to move.

  • Lithosphere (Crust): Rigid and solid outer layer.

Biosphere

• Comprised of all living organisms on Earth.

• Interactions among these organisms and their environments influence the ecosystem.

Hydrosphere/Cryosphere

• Hydrosphere: Encompasses all water bodies, including oceans, rivers, lakes.

• Cryosphere: Portion of the hydrosphere composed of frozen water, such as glaciers and sea ice.

Material Interchangeability in Earth Systems

• States of matter can interchange across Earth systems depending on temperature and pressure conditions.

Earth’s Differentiation

• Process by which different materials segregated into layers of varying composition and density.

Role of Stromatolites and Banded Iron Formations (BIF)

• Stromatolites:

  • Layered sedimentary formations created by the activities of microorganisms, primarily cyanobacteria.

• Banded Iron Formations (BIF):

  • Sedimentary deposits consisting of alternating layers of iron-rich minerals and silica.

  • Formed during the Great Oxidation Event, indicating the presence of oxygen in ancient oceans.

Development of Earth’s Oceans

• Initially formed from volcanic outgassing, water vapor cooled and condensed to fill basins.

• Further influenced by contributions from comets and meteorites containing water.

Anorthosite and the Moon

• Anorthosite:

  • A type of rock primarily composed of plagioclase feldspar.

  • Often associated with the lunar highlands; provides insights into the Moon's formation and history.

Tides

• High Tides and Low Tides:

  • High tides occur when the Moon is directly overhead or on the opposite side of Earth.

  • Low tides occur at right angles to the Moon's position.

• Neap Tides vs. Spring Tides:

  • Neap Tides: Occur when the Moon is at first or last quarter, lower tidal range.

  • Spring Tides: Occur during new or full moons, higher tidal range.

Oceans of the World

• Five modern oceans:

  • Pacific Ocean (largest)

  • Atlantic Ocean

  • Indian Ocean

  • Southern Ocean

  • Arctic Ocean (smallest)

Earth’s Magnetic Field

• Magnetosphere:

  • The area around Earth influenced by its magnetic field.

• Generated by movement of molten iron in the outer core, creating magnetism.

Layers of the Earth

• Label the layers:

  • Inner Core: Solid

  • Outer Core: Liquid

  • Mesosphere: Rigid

  • Asthenosphere: Plastic

  • Lithosphere: Rigid

Theory of Plate Tectonics

• Describes the large-scale movement of Earth's lithosphere, which is divided into tectonic plates.

• Evidence for continental drift includes:

  • Fossil correlatives across continents.

  • Similar rock formations and mountain ranges.

  • Continents fit together like a puzzle.

Plate Boundaries

• Three types of plate boundaries:

  • Convergent: Plates move toward each other, causing mountain formation or subduction.

  • Divergent: Plates move apart, leading to seafloor spreading.

  • Transform: Plates slide past each other, causing earthquakes.

Convergent Plate Boundaries

• Three types:

  • Oceanic-Continental: Subduction leads to volcanic arcs.

  • Oceanic-Oceanic: One plate subducts beneath another, forming deep ocean trenches.

  • Continental-Continental: Collision leads to mountain building.

Right-Lateral vs. Left-Lateral Transform Boundaries

• Right-Lateral: Opposite side moves to the right.

• Left-Lateral: Opposite side moves to the left.

Oceanic Crust Formation

• New oceanic crust forms at mid-ocean ridges (MOR) and is destroyed at subduction zones (trench).

Sea Floor vs. Continents

• Basalt: Found on the ocean floor; denser, lower in SiO2 content.

• Granite: Found in continents; less dense, higher in SiO2 content.

Magnetic Anomalies

• Magnetic anomalies are irregularities in the Earth's magnetic field.

• Used to determine rates and directions of plate motion by analyzing the alignment of minerals in the rocks.

Hot Spot

• A hot spot is an area of volcanic activity caused by a plume of hot material rising from deep within the Earth.

• Prominent hot spots discussed include:

  • Hawaiian Islands

  • Yellowstone

  • Iceland

Detrital Sedimentary Rocks

• Types of sedimentary rocks (from largest to smallest grain size):

  • Breccia

  • Conglomerate

  • Sandstone

  • Siltstone

  • Shale

• Grain size indicates the energy of the depositional environment; larger grains suggest high-energy conditions.

Chemical Sedimentary Rocks

• Precipitates: Formed by chemical precipitation from solutions.

• Evaporites: Formed from evaporation of water, leaving minerals behind.

• Biochemical Sedimentary Rocks: Comprise organic material; e.g., calcium carbonate or silica ooze.

Continental Margins

• Active Margin: Characterized by tectonic activity, thicker sediments, and features like trenches.

• Passive Margin: Featureless, with a gradual increase in continental shelf height.

Marine Sedimentation

• Neritic Sediments: Found in shallow water, typically close to land.

• Pelagic Sediments: Found in deeper ocean regions, includes fine materials such as clay and plankton remains.